Image diagnosis apparatuses are widely used for diagnosis of arteriosclerosis or for preoperative diagnosis at the time of intravascular treatment with a high performance catheter such as a balloon catheter or stent, or for confirming the result after surgery.
An optical coherence tomography diagnostic apparatus (OCT: optical coherence tomography) is one of the imaging apparatuses for diagnosis, and a polarization sensitive OCT is further included in the optical coherence tomography diagnostic apparatus.
The polarization sensitive OCT is for obtaining polarization characteristics of a site to be diagnosed (sample) of a test object. The polarization sensitive OCT obtains the polarization characteristics of the sample based on interference light between reflected light from the sample with respect to a plurality of incident lights having different polarization states and reference light (Japanese Patent No. 5787255).
In the case of switching the polarization state of light from a light source based on a timing (A line trigger) of the same frequency as the light source of wavelength sweeping light, if interference waves are collected according to an A line trigger, corresponding interference waves can be obtained according to switching order of the polarization states of the light. However, the timing (frequency) of collecting interference waves varies, for example, according to the number of collection lines per one revolution of a motor inside a motor drive unit for rotating an imaging core, so in this case, the corresponding interference waves are not necessarily obtained in the switching order of the polarization states of the light.